In a bid to prevent a collapse of Lehman from setting off a chain reaction of financial ruin on Wall Street, the Federal Reserve announced late Sunday night that it was easing the terms of its emergency lending to securities firms.

BofA purchase of Merrill will make a…

Investment players

Stocks tumble amid new Wall Street landscape

And a group of 10 global commercial and investment banks agreed to ante up $70 billion for a fund that any of them could access for emergency cash. The lending pool is intended to protect the participating firms from a sudden investor retreat of the kind that crushed Lehman, until only weeks ago the nation’s No. 4 securities firm.

“This is frightening as hell,” said Richard X. Bove, an analyst at Ladenburg, Thalmann & Co. “We simply have no idea what will happen [today] but we can be pretty sure that it’s not going to be positive.”

The Fed and industry announcements came after a frenzied day in which government officials and industry executives scrambled unsuccessfully to find a buyer for Lehman, then turned their attention to Merrill and insurance giant American International Group Inc., which like Lehman have recorded large mortgage-related losses.

Early today New York time, Lehman issued a statement saying it intended to file for protection under Chapter 11 of the Bankruptcy Code. The company said customers of its brokerage arm and its Neuberger Berman asset management unit could continue to trade and otherwise access their accounts.

The crumbling of Lehman and buyout of Merrill came only one week after the government committed up to $200 billion to shore up home-loan giants Fannie Mae and Freddie Mac. And it came six months after investment bank Bear Stearns Cos., the first big Wall Street victim of the housing crisis, was acquired by JPMorgan Chase & Co. with federal assistance.

After enduring withering criticism of those rescues, the Treasury Department and Federal Reserve ultimately refused to commit taxpayer money to salvaging Lehman, prompting Bank of America and British bank Barclays to withdraw from talks to acquire the 158-year-old firm.

Early signs indicated that investors were unnerved by the day’s events as U.S. stock-index futures — essentially bets on the direction of the stock market — tumbled more than 3% Sunday night. Many Asian stock markets were closed today, but others fell sharply.

A few hours after the Lehman talks collapsed, Merrill, the nation’s largest brokerage, agreed to a $29-a-share buyout by Bank of America. The price is 70% more than Merrill’s closing stock price Friday, but is also 70% below the stock’s all-time high of $97.53 set in January 2007.

It had been hoped that the propping up of Fannie Mae and Freddie Mac would put a floor under the sagging housing market, which in turn would patch holes in the balance sheets of banks and brokerages that hold billions in mortgage-related securities on their books. And, in fact, financial stocks on average rallied last week in the wake of the government’s move.

But investors continued to pound the stock of Lehman, Merrill, AIG and other firms with significant exposure to the mortgage market. Lehman’s stock plunged 77%, Merrill’s sank 36% and AIG’s tumbled 46%.

The expected bankruptcy filing by Lehman would put an end to a firm that began as a cotton trader in 1850 and had endured several near-death blows over the years, including one caused by the meltdown of Long-Term Capital Management a decade ago.

Lehman was known as a gritty overachiever, which it displayed when its headquarters across the street from the World Trade Center were badly damaged in the September 2001 terrorist attacks. For weeks, the company operated out of hotel rooms around the city.

The company posted sizzling profits in recent years as it expanded beyond its longtime roots as a bond-trading operation.

However, like Bear Stearns, Lehman was among the most aggressive backers of the boom in high-risk mortgages early this decade.

Wall Street provided billions of dollars in funding to non-bank lenders like Southern California’s Ameriquest Mortgage Co. and New Century Financial Corp. The lenders specialized in borrowers who had bad credit, huge debt loads, or an unwillingness to document their earnings – and often all of the above.

The Wall Street banks purchased the mortgages and used pools of the loans to back complex bonds, many of which were sold overseas. But heavy defaults beginning in late 2006 triggered the crisis that has brought some financial firms to the brink of extinction. Wall Street firms have written down the value of their mortgage-related holdings by more than $500 billion, giving many of them a need to raise capital.